First of all there should be no "loyalty" to a certain dive shop unless you feel it has truly been earned.
You are not married to them and you should put your budget and peace of mind first.
I mean people go to different car dealerships,restaurants,clothing stores,etc to get the best deal and the dive industry is no different than any other industry.
I think it should be a balance between what your comfortable with price wise and what kind of after purchase service they offer.
I’ll gladly pay a few dollars more if I know the shop will honor the warranty and try to take care of me should things go wrong.
I give all dive shops a chance to earn my business and out of the 5 in my area 3 of them have proven they deserve it.
I think it’s natural to want to be somewhat loyal to the shop you git certified in because of familiarity but to do so blindly is just plain silly.